Do the plants in your vegetable garden seem to perk up when you approach with a sprinkling can? Do the radishes fight with the rutabagas to get extra drops while the potatoes get red-eyed and just lay around after a good dousing? It could be that you’re giving your plants treated human wastewater and they may be getting drugged from it. Could this be affecting the humans who eat them?
Since about half of Israel’s farmers irrigate their crops with treated human wastewater, soil scientists at Hebrew University decided to see what affect it’s having on the soil and plants nourished by it. They tested both for 14 common drugs and two metabolites of one drug, with sweet potatoes and carrots as the crops and used the same treated water farmers get from the city of Kiryat Gat, Israel.
According to their report in Chemical and Engineering News, the researchers found caffeine and the epilepsy drugs lamotrigine and carbamazepine and a metabolite of carbamazepinem an anti-seizure medication. These are nonionic organic molecules that can pass through cell membranes or roots easily.
They then looked at the threshold of toxicological concern (TTC) for the detected drugs. The European Food Safety Authority uses this to determine levels of toxicity that are harmful to humans. The researchers found that an adult would have to eat hundreds of kilograms of sweet potatoes or carrots to reach the limits for caffeine or carbamazepine, but a child would exceed the TTC level for lamotrigine by eating just half a carrot.
More TTC testing for more pharmaceuticals is planned, since farmers in Africa, Asia, Mexico and the U.S. states of California and Arizona are already irrigating with treated human wastewater and more are planning on it, especially in drought-stricken areas.
Is the solution to drugged vegetables better testing, better water treatment, better care for our climate and natural resources or less drug use by the humans creating the waste water?